For the last three (3) decades, magnetic data storage has remained the cornerstone for machine-readable data storage. In the 1970's, research efforts were devoted to investigate new generations of data storage devices based on nonmagnetic principles, such as optical data storage systems. Whereas magnetic data storage disks provide excellent access time and erasability, optical data storage systems can provide a unique combination of superior performance features that make them most appropriate for large memory applications. Optical data storage disks promise to offer low cost-per-bite, improved accessing characteristics and higher storage efficiency. Several optical data storage techniques have been developed which have increased the possible data storage density of a storage device by several orders of magnitude. However, the majority of these types of optical storage systems are non-erasable or Write Once Read Many (WORM) systems. While such WORM systems are useful for library or archive applications, the fact that they are not erasable limits their usefulness.
One such WORM system was disclosed in U.S. Pat. No. 4,999,810, entitled Surface-Enhanced Raman Optical Data Storage System by the present inventor which is incorporated by reference herein. While the Surface-Enhanced Raman Scattering (SERS) phenomenon provides for high density optical data storage, it suffers from the same limitations as do other WORM systems.
The SERS phenomenon is based upon the interaction between a SERS-active support layer and a SERS-active optical layer. Research has taught that emission of radiation based on the SERS effect is highly dependent upon the interaction between the optical layer and the support layer or medium and that minute changes in either layer result in markedly changed SERS emissions. In fact, provided the equipment has sufficient resolution, changes in SERS emissions can result from changes in either the optical layer or support layer at the molecular level. It is this fact that provides a Surface-Enhanced Raman Optical Data Storage (SERODS) system with extremely high data storage density capacity.
It is an object of this invention to provide an improved SERODS system for high density optical data storage based upon the SERS effect. It is an additional object of this invention to provide a SERS based system that is erasable. It is a further object of this invention to provide an optical system that, when used with an appropriate high density SERS storage device, is capable of reading and/or writing data at or near the molecular level.